Endurance
Endurance (also related to sufferance, forbearance, resilience, constitution, fortitude, persistence, tenacity, steadfastness, perseverance, stamina, and hardiness) is the ability of an organism to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from and have immunity to trauma, wounds, or fatigue.
[citation needed] The act of gaining endurance through physical activity decreases anxiety, depression, and stress, or any chronic disease[dubious – discuss].
In military settings, endurance is the ability of a force[clarification needed] to sustain high levels of combat potential relative to its opponent over the duration of a campaign.
[9] Gene expression in muscle is largely regulated, as in tissues generally, by regulatory DNA sequences, especially enhancers.
As reported by Williams et al.,[12] the average distance in the loop between the connected enhancers and promoters of genes is 239,000 nucleotide bases.
This includes genes producing proteins and other products secreted into the systemic circulation, many of which may act as endocrine messengers.
Four days after an endurance type of exercise, many genes have persistently altered epigentically regulated expression.
Biopsies of the vastus lateralis muscle showed expression of 13,108 genes at baseline before an exercise training program.
[13] In a study by Lindholm et al.,[13] twenty-three 27-year-old, sedentary, male and female volunteers had endurance training on only one leg during three months.
An active enhancer regulatory region is enabled to interact with the promoter region of its target gene by formation of a chromosome loop. This can allow initiation of messenger RNA (mRNA) synthesis by RNA polymerase II (RNAP II) bound to the promoter at the transcription start site of the gene. The loop is stabilized by one architectural protein anchored to the enhancer and one anchored to the promoter, and these proteins are joined together to form a dimer (red zigzags). Specific regulatory transcription factors bind to DNA sequence motifs on the enhancer. General transcription factors bind to the promoter. When a transcription factor is activated by a signal (here indicated as phosphorylation shown by a small red star on a transcription factor on the enhancer) the enhancer is activated and can now activate its target promoter. The active enhancer is transcribed on each strand of DNA in opposite directions by bound RNAP IIs. Mediator (a complex consisting of about 26 proteins in an interacting structure) communicates regulatory signals from the enhancer DNA-bound transcription factors to the promoter.
DNA in the nucleus generally consists of segments of 146 base pairs of DNA wrapped around nucleosomes connected to adjacent nucleosomes by linker DNA . Nucleosomes consist of four pairs of histone proteins in a tightly assembled core region plus up to 30% of each histone remaining in a loosely organized polypeptide tail (only one tail of each pair is shown). The pairs of histones, H2A, H2B, H3 and H4, each have lysines (K) in their tails, some of which are subject to post-translational modifications consisting, usually, of acetylations [Ac] and methylations {me}. The lysines (K) are designated with a number showing their position as, for instance, (K4), indicating lysine as the 4th amino acid from the amino (N) end of the tail in the histone protein. The particular acetylations [Ac] and methylations {Me} shown are those that occur on nucleosomes close to, or at, some DNA regions undergoing transcriptional activation of the DNA wrapped around the nucleosome.